The Mets always look stunning in April and start crumbling by September, so fans say it’s only fitting their new stadium is imploding on cue.

“Taxpayers got hosed pretty good,” Ted Flanagan, 48, said before yesterday’s game. “We paid for this place, not [owner Fred] Wilpon — and at $850 million, how come stuff is so shoddy?”

As The Post reported yesterday, the luxury suites at Citi Field are leaky and moldy, tiles have been falling apart, electrical systems are shorting out throughout the building, and concrete panels have fallen off the walls, according to sources who’ve seen the damage.

Of the luxury suites, Jerry Seinfeld’s appears to have been the most damaged, prompting the owner of the $500,000-a-year suite next door to wonder if the comic was contemplating becoming a Yankee fan.

The leaks, which sprang last month, have caused extensive mold to spread throughout the luxury suites.

According to sources, a broken elevator recently forced owner Wilpon to climb four flights of stairs.

Sources at the park also say that huge signs have collapsed, outfield drains have clogged and there are numerous faulty air-conditioning systems and electrical outlets.

Mets execs deny much of the damage and insist the park is “a world-class entertainment facility.”

Like many fans, Chris Buckley, 30, said maybe the Mets should have kept their old ballpark, Shea Stadium, and used the money to sign new players.

“Only the Mets can build an $850 million stadium and have it fall apart,” said Buckley, who owns a cement company.

Although most fans said the new park was still better than the one it replaced, some are still pining for Shea.

“I am all for rebuilding Shea — it was a dump, but it was our dump,” Eddie Boison said.

As for the leaky suites, Boison said it serves those fans right.

“You shouldn’t be coming here to sit in a luxury box anyway,” he said. “It just takes away from the game.”

Fans said they would not shed a tear for Seinfeld, or the other well-heeled fans who seem most affected by the problems, because it’s the taxpayers who have been hit hardest.

But like a true die-hard fan, Alan Wunner, 56, is taking the “wait ’til next year” approach.

“They had to build to meet a deadline,” he said. “Whatever problems are being exposed now, I am sure they will be addressed by the team by next season. There are far worse ways the government wastes my money.”